Do You Need a Control Group?

In the social sciences, suppose you're interested in analyzing the effects of the minimum wage. And so one thing we can do is look to see what happens when a particular state raises its minimum wage. How does that affect like, let's say teenage employment? So you might think, oh, it's pretty straightforward. But there's all sorts of things going on in the economy that could affect the teen unemployment rate in a particular US state. In this kind of work, they actually don't use the unemployment rate. Okay, I'm not going to get into why, but that's just say no.